Frederick w



(New F. w. GORDON.

DASH POT.

w w 9 m m w W m m 6 M m. Tm e 1 S H 4 I V /7/M%// Mi w m 1 e M W W P M 2 1 H H 1 M r 1 8 I K% e x E w m .I M M IIIIIIJMJWIM m 1.

UNITED STATES PATENT OFFICE.

FREDERICK W. GORDON, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE PHILADELPHIA ENGINEERING \VORKS, LIMITED, OF SAME PLACE.

DASH-POT.

SPECIFICATION forming part of Letters Patent No. 541,351, dated June 18, 1895. Application filed May 19, 1894. Renewed April 20, 1895. Serial No. 546,533. (No model.)

To all whom it may concern:

Be it known that I, FREDERICK W. Gon- DON, of Philadelphia, Philadelphia county, Pennsylvania, have invented certain new and useful Improvements in Dash-Pots, of which the following is a specification.

This invention pertains to improvements in dash-pots for use in connection with valve gear of releasing type such, for instance, as

1 o the well known Corliss gear, the objects of the improvements being to enhance the accuracy of the performance at specially high speeds and to secure noiselcssness of action.

My improvements will be readily understood from the following description, taken in connection with the accompanying drawings, in which- Figurel is a vertical section of a dash-pot, exemplifying my invention; Fig. 2, a similar section, enlarged, of the upper portion; Fig. 3, a plan, and Fig. 4: a horizontal transverse section and plan.

In the drawings, 1, indicates a base-plate adapted to be secured, as usual, to a solid floor or foundation; 2, a piston rigidly secured thereto and projecting upwardly therefrom, this piston being hereinafter termed the cushion-piston, its office being to furnish the cushioning arrest for the valve gear parts which the 0 dash-pot operates; 8, a cylinder fitting upon this stationary piston and reciprocating upon it and closed at the top; 4, guide-studs standing rigidly up from the base-plate and engaging guide holes in lugs 0n the cylinder to keep 5 the cylinder from turning upon the piston; 5, segmental slots in the base-plate engaged by the studs 4 and permitting of those studs being adjusted around so as to put the cylinder in selective angular relations to the piston; 6, a partition in the cylinder forming the topfor that portion of the cylinder in which the cushion-piston works, this partition being separably inserted into the cylinder; 7, screws going through the wall of the cylinder and engaging the partition 6 and holding that partition in a fixed position in the cylinder; 8, piston-rod projecting upwardly from the cushion-piston, the partition 6 sliding on this rod; 9, diagonal or spiral ports in the wall of the cylinder below the partition 6; 10, passages from the ports 9 to the cylinder space just above the partition 6, these passages being formed by side pipes castupon the cylinder and ported at their upper ends; 11, diagonal or spiral notches in the upper face of cushion-piston 2, the bases of these notches corresponding with the spirality of the ports 9 which they engage; 12, a second piston in the cylinder, above the partition 6, and fast on the piston-rod 8, this second piston being hereinafter termed the suctionpiston, it being its oftice to furnish the vacuum for moving the valve gear parts controlled by the dash-pot; 13, the usual rod coming down from the valve gear and to operate upon the valve gear by downward motion, this rod being attached to the cylinder 3 so that as the valve part in question rises the cylinder will be raised, and as the cylinder is sucked down again the rod and valve part will be pulled down; 14, a segment of a ball on the lower end of rod 13; 15, a socket secured in the top of the dash-pot cylinder, the ball-end of rod 13 being disposed within this socket; 16, a gland screwed into the socket 15 over the 'ball-seg- 7 ment lat so that the rod may freely rock or turn, this gland being split diametrically so that it may be gotten into place notwithstanding the enlargement formed on the end of the rod by the ball-segment, and such enlargement as might be at the upper end of the rod for permitting of its convenient attachment to a valve-gear part; 17, a spring within the socket 15, resting on the floor of that socket and pressingup upon the enlarged end of rod 13 and holding the ball-segment nicely to its bearing; 18, a cylindrical valve body screwed into the top of the cylinder; 19, a valve screwed down into a threaded socket in this valve body and having a bearing-seat in the 0 base thereof; 20, an adjusting screw screwed into the top of a socket in valve 19; 21, a ball s valve in the base of the'socket in valve 19, closing an aperture leading through the base of valve 19; 22, a light spring holding the ball 5 to its seat and adjusted in tension by means ofscrew 20; 23, holes leading from the atmosphere into the socket in valve-body 18; 24, hole from the base of the socket in valve-body 18 communicating with the interior of cylinroo when screwed down tight, cutting 0E communication between this hole and holes 23, the

seating of valve 21 then closing all upward passage from hole 24; 25, hole through ad justing screw for the escape of air passing up'through hole 24 and leaving the ball-valve; 26, the upper end of cylinder 3; 27, cylinder space between partition 6 and suction-piston 12; 28, cylinder space between piston 12 and the top of the cylinder, and 29, cylinderspace between partition 6 and top of piston 2.

' The cylinder 3 is the vertically reciprocating part and it comes down so far that partition 6 will strike the top of piston2, the top 26 of the cylinder then coming down to the topof piston 12. Cylinder space 27 will then have its full extent, equal to the full stroke of the cylinder, and it is immaterial how much more length that space has. With the cylinder in such position, clear down, the steam valve controlled by the dash-pot'will be shut. The opening of the steam val ve,in the usual manner, pulls on rod 13 and quickly lifts the cylinder, and enlarges the space 28,

, producing more or less of a vacuum therein,

' which the descent takes place.

and upon the release of the valve gear the suction exerted by this vacuum will quickly pull the cylinder down to former position and close the steam valve sharply. Should there be sufficient air in cylinder space 28 to produce, under compression, a pressure above that of the atmosphere plus the weight of the ball-valve 21, the ball valve will lift and the air will escape at hole 25, spring 22 being designed, not to increase the load upon the valve but merely to insure its seating. By opening valve 19 the vacuum may be relieved when desired.

As the cylinder starts down from the top of its stroke the air in cylinder space 29transfers freely into enlarging space 27 through ports 9 and passages 10. In the course of the down stroke of the cylinder ports 9 will pass the face of cushion-piston 2, the transfer of air then becoming arrested and the air that is then confined in cylinder space 29 becoming compressed between the cushioning-piston and the partition, this compressed air forming the arresting cushion. The degree of compression will be dependent upon the time in the stroke at which ports 9 become out off by the cushioning piston, and the cushioning effect of this compression will be dependent upon the weight of the parts and the speed at The cylinder can be turned upon the cushioning piston by adjusting the studs 4, thus causing the cushioning piston to close ports 9 earlier or later in the stroke, thus altering the amount of air pent up in the cylinder space 29. This ad justment can be so made that the cylinder may descend at any practicable engine speed for release gear engines and permit of the sharp descent of the cylinder and of its proper cushioning at the foot of the stroke, it being quite practicable to let the partition 6 come right downon top of the cushioning piston, the possible adjustment of the air cushion providingfor' a cushioning film'of air under such compression as will insure silence in operation. On the up stroke of the cylinder after ports 9 open, air simply transfers from cylinder s action being entirely silent.

It being possible, in this device, to work with clearances so small as to be virtually metal to metal contacts, provisionis made for conveniently constructing the device with small clearance. Before drilling for screws 7 the partsare assembled and the cylinder pushed down to piston 12,1oose partition 6 being allowed to reston top of piston 2. Then the drilling is done for screws 7 whereby the partition becomes fixed in the proper position, thus avoiding the necessity for such close workmanship as will be called for byordinary methods for securing accuracy in two separateclearancespaces. Theemploymentof-the partition 6, asa separable part, also permits of the cylinder being bored through as a single cylinder, the hole in which socket 15 is screwed into the top of the cylinder per mitting the use of a strong boring bar in the operation of boring the cylinder, there thus being an insurance that the cylinders of the two pistons will be truly in line with each other.

Dash-pot rod 13 has only tensional work to do, and spring 17 keeps itup to its seat in gland 16. The split in gland 16 permits of its I application to the dash-pot rod when the rod is enlarged at both ends. Valve-body 18 is split, as seen in Fig. 1 so as to grip valve 19 and prevent its adjustment being disturbed by shock. By slacking up valve 19 a trifle an air way is opened from holes'23 to cylinder space 28.

It is to be understood that the structure illustrated is merely exemplifying in charac V ter and that the invention may find its embodiment in variously modified forms.

-I claim as my invention- 1. In a dash-pot, the combination, substantially as set forth, of a cylinderhaving an outlet-port, a cushion'piston arranged to overrun said port and having a spiral face, and means for adjusting the angular relation of the piston to the cylinder.

2. In a dash-pot, the-combination, substantially as set forth, of a cylinder having a spiral outlet-port, a cushion-piston arranged to overrun said port and having a spiral face, and means for adjusting the angular relation of the piston to the cylinder.

3. In a dash-pot, the combination, substantially as set forth, of acylinder having a spiral outlet port, a cushion-piston arranged to overrun said port and having aspiral face, and circumferentially adjustable guide-studs con meeting the cylinder and piston and holding the two in selected angular relation.

4. In a dash-pot, the combination, substantially as set forth, of a pair of cylinders connected by ports and side-pipes, and a pair of connected pistons, one in each of said cylinders', one of said pistons being arranged to overrun its cylinder-port,whereby air is transferred from one cylinder to the other and then the How out off by such overrunning piston and the remaining air compressed in one cylinder to form a cushion.

5. Ina dash-pot, the combination, substantially as set forth, of a cylinder having a uniform bore from end to end, a transverse partition therein, a piston below and a piston connected therewith above said partition, and connected ports above and below said partition between the pistons.

6. In a dash-pot, the combination, substantially as set forth, of a cylinder having two connected ports in its wall, a pair of connected pistons, and a separable transverse partition fitting the bore of and secured in the cylinder between the two ports and between the two pistons.

7. In a dash-pot, the combination, substantially as set forth, of a cylinder having two connected ports in its wall, a pair of connected pistons, a transverse partition separably disposed in the cylinder between said two ports and between said two pistons, and pins engaging the cylinder-wall and partition and securing the partition in place.

8. In a dash-pot, the combination, substantially as set forth, of an upstanding stationary screwed into said valve-body, a valve in said socketed valve, a spring over said valve, and an adjusting screw screwed into the socketed valve over the spring.

10. In a dash-pot,the combination, substantially as set forth, of a dash-pot cylinder and a piston, a socket for a motion-rod,'a motionrod having a ball-segment in said socket, a split gland in the socket over the bail-segment, and a spring in the socket under the ball-segment.

FRED. W. GORDON.

WVitnesses:

J OHN C. ATKINSON, Jos. L. ATKINSON. 

